(1) Field of the Invention.
The present invention relates to nail clippers. More particularly, the invention disclosed herein relates to nail clippers having guides preventing the clipping of fingernails or toenails too close to the tip of the finger or toe; besides preventing laceration of the tip of such digits, the guide also stabilizes the clipping procedure for the user. Moreover, the disclosed invention enables the user to maintain his or her nails at a desired length. More particularly, the present invention includes nail clippers having adjustable stops for adjusting the distance between the clipping edge and the finger or toe having the nail to be clipped.
(2) Background of the Invention.
Hygienic maintenance of fingernails and toenails can be important to personal health and mobility, but can be difficult for some people. This is especially true for those with impaired vision, dexterity or equilibrium.
Scientific research has determined that, with age, there is a rapid decrease in the growth rate for both toenails and fingernails. As a result, both kinds of nail usually thicken, because of the accumulation of nail cells (called onychocytes). Other factors that can affect the rate of thickening include long-term trauma and impaired circulation. Trauma from falling objects, stubbing injuries, athletic wear and tear, and poorly fitting shoes can alter the cells from which the nails grow; and repetitive incidents or one severe episode can thicken or disfigure the nail plate.
Peripheral arterial disease, which impairs circulation, most often affects the feet and can also cause thickened, brittle nails. As nails become harder and thicker, ingrown toenails may be more common. The tips of the fingernails may also break. Moreover, lengthwise ridges may develop in the fingernails and toenails. With advancing age, normal characteristic changes in the growth rate and morphology of the nail plate occur. Nail plate growth rates of fingernails and toenails normally average 3.0 and 1.0 mm/mo, respectively. With advancing age, starting at the age of 25 years, this rate tends to decrease by approximately 0.5% per year. Various changes in nail plate thickness might occur, typically becoming thicker but in some instances becoming thinner. A decrease in the longitudinal curvature and an increase in the transverse convexity characterize senile changes in the contour of the nail plate. As for texture, there is usually a tendency of the normally smooth nail plate texture to become progressively more friable with increasing age, resulting in fissuring, splitting, and longitudinal superficial or deep striations. Each of these makes hygienic maintenance of nails more difficult.
According to a paper published in Can Fam Physician (the official publication of the College of Family Physicians of Canada, 2011 Feb; 57(2): 173-181), many nail disorders affect the population in general; however, they might appear with increasing frequency with advancing age and include brittle nails, onychauxis, onychocryptosis, infections (especially onychomycosis), onychoclavus, subungual hematoma, splinter hemorrhages, and malignancies of the nail apparatus.1,2,3,4 
Brittle nail disorder is considered a polymorphic abnormality characterized by increased fragility of the nail plate. It affects around 20% of the population, with increased incidence in women and in older people.3 It manifests clinically with varying severity of onychoschizia or onychorrhexis. Onychoschizia is usually caused by impairment of intercellular adhesion between the corneocytes that make up the nail plate. This results in transverse splitting of the nail due to breakage of the lateral edges of the nail plate, and in lamellar splitting of the free edge and distal portion of the nail plate. On the other hand, onychorrhexis frequently manifests as nail plate splitting or ridging, longitudinal thickening, or multiple splits leading to triangular fragments at the free edge. Onychocryptosis occurs when the nail plate penetrates into the adjacent lateral nail fold secondary to nail plate overcurvature, subcutaneous in-growing toenail, or lateral nail fold hypertrophy. It manifests clinically with inflammation of the lateral nail fold, which might be associated with granulation tissue and secondary infection. Although more common in young adults, onychocryptosis might infrequently be encountered in older persons, resulting in substantial pain, walking difficulties, and disability.1,2,4 Underlying causative factors include inappropriate nail cutting.